SBI Lynx 180B Lower Info and Feedback, for WK, MCR, and AR180B
- Thread starter Ustauk
- Start date
The Kodiak lower works now. I ended up enlarging and polishing the feed ramp a bunch and that made the KD lower work great.
Found an issue with the Lynx lower though. The mags are super floppy fore and aft. If I put some forward pressure at the base they work fine(except for pistol mags with more than 5 rounds) but if the bottom of the mag flops back, even my enlarging/polishing of the feed ramp wasn't enough and rounds just jam.
I wonder if it has anything to do with the shape of the 7.62x39 rounds and mags compared to the .223? There's so much play it's easy to see how bad of an angle the rounds are at when there's any pressure on the front of the mag. I'm certainly not an expert so who knows but I'd really like to get this thing running and put a Zhukov stock on it.
Found an issue with the Lynx lower though. The mags are super floppy fore and aft. If I put some forward pressure at the base they work fine(except for pistol mags with more than 5 rounds) but if the bottom of the mag flops back, even my enlarging/polishing of the feed ramp wasn't enough and rounds just jam.
I wonder if it has anything to do with the shape of the 7.62x39 rounds and mags compared to the .223? There's so much play it's easy to see how bad of an angle the rounds are at when there's any pressure on the front of the mag. I'm certainly not an expert so who knows but I'd really like to get this thing running and put a Zhukov stock on it.
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well, my x39 pistol mags do look a weeeeee bit shorter than my 556. doesn't seem a lot, but perhaps enough to introduce some play? that would really suck if the sbi lowers didn't work w x39. i'd have to sell mine on the ee for $600 like all those other dbs. mine should be showing up in a week or so and i can test with my x39 pistol mags and upper.
- Location
- Sherwood Park, AB
I would like to take this opportunity to thank everyone who participated in our pre-order program. As we're all aware pre-orders in this country are a rough experience full of delays. Thankfully all of our customers were great and didn't harass us for updates, which really allowed us to focus on production and deliver all pre-orders on time.
- Location
- Sherwood Park, AB
For people use WK parts, on a lot of bolts we've found that a burr will form on the lugs and can cause feed issues when switching between lowers and different ammo. This isn't specifically related to the Lynx but we've had a few customers with this issue so it's worth sharing the fix. If your bolt has a burr or sharp edge on the bolt it can dig into the next case in the mag when feeding and cause all kinds of jams. Simply breaking the edge and rounding off the burr fixes the issue. MCR bolts seem fine and we haven't seen the issue there.
So after enough emails back and forth with SBI, I'm sure they regret selling me a lower... But honestly they have answered a bunch of probably stupid questions and responded to my ideas etc. a bunch.
With their help pointing out what to look for, the bolt is contacting the top of my mags causing my feeding issues. I measured the distance to the top of the mag catch and it is smaller by about 0.020" on the Lynx. They are going to send me some measurements to make sure my lower is within spec but they mentioned the Wks can be off as well.
If I put a bit of forward pressure at the back of the mag and keep it there, everything runs great. It even emptied a full pistol mag which the stock WK won't do.
I'm at a spot I need to make a decision. Mod the mag catch and see what happens, or wait for an upper (more $$$) and hope it runs better with my lower.
All that being said I appreciate the hand holding SBI is doing with this idiot
With their help pointing out what to look for, the bolt is contacting the top of my mags causing my feeding issues. I measured the distance to the top of the mag catch and it is smaller by about 0.020" on the Lynx. They are going to send me some measurements to make sure my lower is within spec but they mentioned the Wks can be off as well.
If I put a bit of forward pressure at the back of the mag and keep it there, everything runs great. It even emptied a full pistol mag which the stock WK won't do.
I'm at a spot I need to make a decision. Mod the mag catch and see what happens, or wait for an upper (more $$$) and hope it runs better with my lower.
All that being said I appreciate the hand holding SBI is doing with this idiot
- Location
- Sherwood Park, AB
So after enough emails back and forth with SBI, I'm sure they regret selling me a lower... But honestly they have answered a bunch of probably stupid questions and responded to my ideas etc. a bunch.
With their help pointing out what to look for, the bolt is contacting the top of my mags causing my feeding issues. I measured the distance to the top of the mag catch and it is smaller by about 0.020" on the Lynx. They are going to send me some measurements to make sure my lower is within spec but they mentioned the Wks can be off as well.
If I put a bit of forward pressure at the back of the mag and keep it there, everything runs great. It even emptied a full pistol mag which the stock WK won't do.
I'm at a spot I need to make a decision. Mod the mag catch and see what happens, or wait for an upper (more $$$) and hope it runs better with my lower.
All that being said I appreciate the hand holding SBI is doing with this idiot
We don't regret selling you a lower at all!
I suggest moding the mag release since they're cheap and easily replaceable. It seems like your BCG is just not the same as others, or your mag release is way out of spec. FYI, height from the top of the receiver, to the top of the mag release slot should be about 0.8". As long as it's within 0.010" of that you shouldn't have any feed issues. If it's out more than that you'd likely be unable to install a mag release anyways. This will not be the same as the WK, so you can't really compare them. We'll shoot you an email on Monday with the same measurement details.
so, my batch 5 lower showed up today. fast shipping, excellent piece of kit. things i've determined while assembling (ie, plan your lower parts kit order ...):
- TNA extended mag release paddle interferes with the flare on the magwell.
- TNA external bolt catch lever hits TNA AR anti-walk trigger pins.
- taller drop-in triggers like trigger tech interfere with the TNA external bolt catch.
time to start grinding.
- TNA extended mag release paddle interferes with the flare on the magwell.
- TNA external bolt catch lever hits TNA AR anti-walk trigger pins.
- taller drop-in triggers like trigger tech interfere with the TNA external bolt catch.
time to start grinding.
for slop, TNA sells a little rubber o-ring that goes around the locator tab on the rear of the upper that reduces rattle. or, i mean, go to the plumbing section at the local hardware store. or take one from the battery compartment of the wifes vibrator (although she might get a shock in the bath afterwards ...).
lynx takes AR trigger pins, so you want to look for "anti-walk" trigger pins for an AR. available from multiple vendors.
ps, don't do that you your wife.
lynx takes AR trigger pins, so you want to look for "anti-walk" trigger pins for an AR. available from multiple vendors.
ps, don't do that you your wife.
lol,so that’s what the little oring is for. Thanks
I guess I’ll just apply a bit of electrical tape to the pins, until I can get a couple of antis.
Edit. Oring didn’t do much, I guess I can zip tie it together.. lol
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JDForBrkFst
CGN frequent flyer
- Location
- Roughly North Central AB
Radium King. You are the king. That post was hilarious.]
quoting myself here (seems to be a trend in this thread!). spent some time with file and friends yesterday. took down the bolt catch so that it works with the triggertech drop-in trigger. you can use the external bolt catch lever shaft (the part that passes through the receiver) as a trimming template. i think this issue is common to all 180's and is an easy fix.
the mag release paddle puts a bit of diagonal force on the mag release and it can bind due to play in the receiver. not sure if this is common to all 180's, but going to shorten the spring and see if it is as much of a problem with reduced spring tension, otherwise going to bin it and go milspec (anyone want to trade?)..
the safety shaft on shooters right was about 1/8" too long. didn't want to use the $2 shims that sbi sells so just filed it down to fit (if you have the tna unit there is a small bevel on the end of the shaft; file until bevel is gone, then take down the key on the selector the same amount).
there is no good way to fit the tna/kd external bolt catch on the sbi lower. so, i cut the proud end off. requires quite a bit of force to operate now (without the additional leverage) so going to drill/tap the end for a cap head screw to give me some purchase.
that should get the rifle finished. can't test fire until i get some new fasteners in the mail (rwa didn't completely tap the four spots in the receiver that hold the barrel in so the fastener ends were all chewed up and ratching the threads in the receiver). that will get me shooting x39; and when the ibi barrel shows up i'll try and get 6.5 running for a Grrrr180 and can provide some info on what works for gas port size, piston length, etc.
the mag release paddle puts a bit of diagonal force on the mag release and it can bind due to play in the receiver. not sure if this is common to all 180's, but going to shorten the spring and see if it is as much of a problem with reduced spring tension, otherwise going to bin it and go milspec (anyone want to trade?)..
the safety shaft on shooters right was about 1/8" too long. didn't want to use the $2 shims that sbi sells so just filed it down to fit (if you have the tna unit there is a small bevel on the end of the shaft; file until bevel is gone, then take down the key on the selector the same amount).
there is no good way to fit the tna/kd external bolt catch on the sbi lower. so, i cut the proud end off. requires quite a bit of force to operate now (without the additional leverage) so going to drill/tap the end for a cap head screw to give me some purchase.
that should get the rifle finished. can't test fire until i get some new fasteners in the mail (rwa didn't completely tap the four spots in the receiver that hold the barrel in so the fastener ends were all chewed up and ratching the threads in the receiver). that will get me shooting x39; and when the ibi barrel shows up i'll try and get 6.5 running for a Grrrr180 and can provide some info on what works for gas port size, piston length, etc.
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So after checking the wife’s vibrator for o rings apparently her vibrator is much bigger than radiums wife’s.
She told me it’s so she can mimic my high #####. Hmmm.
Anyway, I decided to give it a couple of wraps of electrical tape.
And touch of black nail polish to keep my trigger pins in.
Zero slip now.
Hopefully an accuracy and range test tomorrow.
She told me it’s so she can mimic my high #####. Hmmm.
Anyway, I decided to give it a couple of wraps of electrical tape.
And touch of black nail polish to keep my trigger pins in.
Zero slip now.
Hopefully an accuracy and range test tomorrow.
I have a princess auto O-ring kit that I found one to fit but I had to shave close to half the thickness off to be able to put my upper and lower together. I might make it to the range tomorrow to test it out. I also filed about 0.020” off the top of my mag release so the mag will sit a bit lower. Hopefully these two thing will keep my WK bolt from catching the top of my mags. Cycling dummy rounds is promising so far though.
I just want to mention it again that SBI has been great answering my questions A LOT. I’m looking forward to when they release the upper.
Radium king, just file the edge down on the extended mag release paddle that’s contacting. It doesn’t take much to make it work properly.
I just want to mention it again that SBI has been great answering my questions A LOT. I’m looking forward to when they release the upper.
Radium king, just file the edge down on the extended mag release paddle that’s contacting. It doesn’t take much to make it work properly.
View attachment 555559Apparently I’m confused.. lol
So, do the other Spectre lower solve the slop/wobble issue?
With this much movement, there’s got to be accuracy issues, as the scope will be moving up and down quite a bit.
I put the small o ring on ,that came with my rifle and it didn’t do anything.
So, do the other Spectre lower solve the slop/wobble issue?
With this much movement, there’s got to be accuracy issues, as the scope will be moving up and down quite a bit.
I put the small o ring on ,that came with my rifle and it didn’t do anything.
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